Rollup merge of #155097 - GuillaumeGomez:emit_lint-multispan, r=JonathanBrouwer

Make `rustc_attr_parsing::SharedContext::emit_lint` take a `MultiSpan` instead of a `Span`

I'll likely need it for https://github.com/rust-lang/rust/pull/153721 to allow emitting the lint on one attribute at a time instead of each of the wrong values.

r? @JonathanBrouwer